I make gluten free, egg free, lactose free and halal wedding cakes for the same price as my normal wedding cakes. The only thing I cannot guarantee is that any of my cakes are free from nuts. Also, I cannot make Kosher cakes.
One proviso that I should put on this is that egg-free cakes are very light and fluffy, and as a result tend to go a bit lumpy when covered with icing. You are welcome to have this included with your cake, but I would recommend that I make a separate mini egg free cake to supplement your main wedding cake if this is a requirement of yours.